The 33-year-old was still wearing his watch and had his wallet. But when detectives took inventory of the shop, they discovered a valuable piece of equipment was missing.

A rare, expensive scientific scale, used to measure chemicals, was gone. The scale was worth about $1,800 at the time.

Investigators would later learn it had been stolen, then tracked down months before Singh's murder. Years later, Erickson Armstrong, a former shop employee, was charged with stealing and pawning the scale before Singh was killed.

"(Armstrong) stole it, it was recovered by one of our deputies in '87 and then that's what was stolen again," Bivens said.

Armstrong died four years ago. Detective Terrance Greenwood interviewed Armstrong several times before his death. Greenwood spoke with many of the 15 shop workers. Some of them are still considered "persons of interest."

The scale was never tracked down. Investigators think finding it could be the key to finding the killer.

In 2007, detectives thought they had a break in the case. A hair that had been found in Singh's hand and was thought to belong to the killer, was resubmitted to a crime lab for DNA testing. But it turned out, the hair had been mislabeled. It was actually Singh's own hair.

That setback frustrated detectives, but they're still hopeful they'll find the murderer.